It sounds like something you’d see in a late-night Sci-Fi flick: Scientists have discovered bacteria in a California lake that uses arsenic instead of phosphorous to survive. Arsenic is plentiful in the universe, and so bacteria that uses it to survive suggests the possibility of alien life. But just how likely is it that this bacteria exists in space?

We’re joined now by Caleb Scharf, director of astrobiology at Columbia University, to answer some of the questions on this topic.